A regenerated spandex fiber and a method for preparing the same

Abstract

This invention provides a recycled spandex fiber and its preparation method. The recycled spandex fiber comprises recycled spandex, a crosslinking agent, a mixed amine, and a reinforcing agent reacting to obtain a recycled spinning material, which is then melt-spun to obtain the recycled spandex fiber. The preparation method includes a polymerization step: selectively crushing and drying waste spandex fibers, spandex scraps, or spandex components from waste fabrics to obtain recycled spandex; the drying temperature is 90–200°C; and a spinning step: using the recycled spinning material as raw material, melt-spinning is performed through a spinneret assembly, followed by spinning and winding to obtain the recycled spandex; the spinning temperature is 220–250°C. The recycled spandex raw materials used in this invention are widely available, and the prepared recycled spandex fiber is not only environmentally friendly and pollution-free, but also has good processing performance, and the product exhibits excellent strength, high temperature resistance, and chemical resistance, reaching the performance level of conventional melt-spun spandex fiber products.

Description

Technical Field

[0001] This invention belongs to the field of spandex recycling technology, specifically relating to a recycled spandex fiber and its preparation method. Background Technology

[0002] The green development of spandex is an inevitable trend and is crucial to the core competitiveness of enterprises. Various spandex manufacturers are actively expanding into the recycled spandex field, and there are already numerous patented technologies related to recycled spandex. For example:

[0003] Patent CN112538667A provides a method for regenerating spandex from waste spandex filaments. The method involves mixing dried waste spandex filaments with a non-protic polar solvent, heating to dissolve, and cooling to obtain a waste spandex filament solution. This solution, along with a prepolymer and a chain extender, forms a spandex spinning dope. The regenerated spandex is then produced through solution spinning under nitrogen protection. Patent CN110016730A primarily recovers aqueous waste spandex dope and is suitable for producing spandex filaments with deniers of 140 and above, exhibiting high mechanical properties and resilience. Patent CN115182072A provides a method for recycling waste spandex prepolymer liquid. The waste liquid undergoes a chain extension reaction with mixed amines to obtain polyurethane urea dope solution A. This solution A is then mixed with normally produced polyurethane urea dope solution B, stirred and matured, and then dry-spun to obtain polyurethane urea elastic fibers.

[0004] The aforementioned recycled spandex technologies are all based on dry spinning processes, and the organic solvents used in the production process, such as DMAC, do not meet the requirements of the Global Recycling Standard (GRS) regarding chemicals. The recycled spandex fiber produced by this invention is produced through melt spinning, achieving a raw material recovery rate of up to 100%, and the production process does not use toxic solvents, generating no "three wastes" pollution, fully complying with GRS certification requirements. Furthermore, the molecular chain breakage during the high-temperature melting process of recycled spandex easily leads to poor subsequent spinning processing performance, insufficient product strength, and poor high-temperature and chemical resistance. This invention adds appropriate crosslinking agents and reinforcing agents to the melt spinning process, effectively compensating for the defects of melt-spun recycled spandex. Summary of the Invention

[0005] Technical Problem: The purpose of this invention is to overcome the shortcomings of the existing technology and provide a recycled spandex fiber and its preparation method. The recycled spandex uses recycled spandex as the main raw material, fully recycles and reuses waste spandex, and the recycled spandex prepared by melt spinning has excellent performance, which is basically the same as that of conventional non-recycled spandex, and meets the requirements for use.

[0006] Technical solution: The present invention provides a regenerated spandex fiber comprising the reaction of recycled spandex, crosslinking agent, mixed amine and reinforcing agent to obtain a regenerated spinning material, and the regenerated spinning material being melt-spun to obtain regenerated spandex fiber.

[0007] The sources of the recycled spandex include one or more of the following: spandex waste yarn, spandex scrap, or spandex components from waste fabrics.

[0008] The crosslinking agent includes a polyurethane prepolymer, which is an isocyanate-terminated polyurethane prepolymer obtained by reacting a diisocyanate and a polymeric polyol; the crosslinking agent accounts for 1 to 10% of the total mass of the recycled spandex fiber.

[0009] The NCO content of the terminal isocyanate-based polyurethane prepolymer is 2-6% by mass.

[0010] The diisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and is more preferably diphenylmethane diisocyanate.

[0011] The polymeric polyols include polyether polyols, which include any one or a combination of at least two of polytetramethylene ether glycol, polyethylene glycol, or polypropylene glycol.

[0012] The mixed amine includes an amine chain extender and an amine terminator; preferably, the molar ratio of amine groups in the mixed amine to reactive groups on amine groups in the crosslinking agent is 1.1:1 to 3:1, and the spinning process is carried out in a weakly alkaline environment;

[0013] The amine chain extender comprises a diamine having 2 to 30 carbon atoms, including one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, or hexamethylenediamine.

[0014] The amine terminator comprises a monoamine having 2 to 20 carbon atoms, including one or more of diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, dipropylamine, cyclohexylamine, or ethanolamine.

[0015] The molar ratio of the amine group of the amine chain extender to the amine group of the amine terminator is 10:1 to 30:1.

[0016] The reinforcing agent includes one or more of silicon dioxide, hydrotalcite, silicon carbide, boron oxide, or aluminum oxide; the reinforcing agent accounts for 0.5% to 3% of the total mass of the recycled spandex fiber.

[0017] The method for preparing recycled spandex fiber of the present invention includes the following steps:

[0018] Polymerization step: Selected spandex waste filaments, spandex waste materials, or spandex components from waste fabrics are crushed and dried to produce recycled spandex; the drying temperature is 90-200℃.

[0019] Recycled spandex, crosslinking agent, mixed amine, and reinforcing agent are mixed evenly and reacted fully to obtain recycled spinning material; wherein the crosslinking agent accounts for 1-10% of the total mass of recycled spandex fiber; the reinforcing agent accounts for 0.5-3% of the total mass of recycled spandex fiber; the molar ratio of amine groups in the mixed amine to reactive groups in the crosslinking agent is 1.1:1-3:1; the molar ratio of amine groups to crosslinking agent ensures that the spinning process is weakly alkaline;

[0020] Spinning steps: Using the aforementioned recycled spinning material as raw material, melt spinning is performed through a spinneret assembly, followed by spinning and winding to obtain recycled spandex; the spinning temperature is 220-250℃.

[0021] Beneficial Effects: The recycled spandex raw materials used in this invention have a wide range of sources, including waste spandex fibers, waste spandex materials, or spandex components from waste textiles, all of which can be used as recycled spandex raw materials without the need for complex pretreatment. The recycled spinning material obtained by reacting recycled spandex with specific crosslinking agents, mixed amines, and reinforcing agents can be directly melt-spun to prepare recycled spandex fibers. The fibers not only use green, environmentally friendly, and pollution-free raw materials and have good processing performance, but also exhibit excellent strength, high temperature resistance, and chemical resistance, reaching the performance level of conventional melt-spun spandex fiber products. Detailed Implementation

[0022] The regenerated spandex fiber comprises the reaction of recycled spandex, crosslinking agent, mixed amine and reinforcing agent to obtain regenerated spinning material, and the regenerated spinning material is obtained by melt spinning.

[0023] The sources of the recycled spandex include one or more of the following: spandex waste yarn, spandex scrap, or spandex components from waste fabrics.

[0024] The crosslinking agent includes a polyurethane prepolymer, which is an isocyanate-terminated polyurethane prepolymer obtained by reacting a diisocyanate with a polymeric polyol.

[0025] Preferably, the NCO content of the terminal isocyanate-based polyurethane prepolymer is 2-6% by mass;

[0026] Preferably, the diisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and more preferably diphenylmethane diisocyanate.

[0027] Preferably, the polymeric polyol includes a polyether polyol, which includes any one or a combination of at least two of polytetramethylene ether glycol, polyethylene glycol, or polypropylene glycol, and more preferably polytetramethylene ether glycol.

[0028] In some embodiments of the present invention, the polyurethane prepolymer can also be a recycled prepolymer, the source of which includes isocyanate-terminated polyurethane prepolymer waste generated during the preparation of spandex.

[0029] The mixed amine includes an amine chain extender and an amine terminator;

[0030] The amine chain extender comprises a diamine having 2 to 30 carbon atoms. Preferably, the diamine having 2 to 30 carbon atoms comprises one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, or hexamethylenediamine.

[0031] The amine terminator comprises a monoamine having 2 to 20 carbon atoms. Preferably, the monoamine having 2 to 20 carbon atoms comprises one or more of diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, dipropylamine, cyclohexylamine, or ethanolamine.

[0032] In this invention, the crosslinking agent and chain extender act as bridges between the linear molecules of the original spandex during the reaction process, enabling multiple linear molecules to bond together and form a network structure to improve the overall performance of the recycled spandex.

[0033] The reinforcing agent includes one or more of silicon dioxide, hydrotalcite, silicon carbide, boron oxide, or aluminum oxide;

[0034] In some embodiments of the present invention, the reinforcing agent has a nanoscale particle size;

[0035] In this invention, an appropriate amount of reinforcing agent is used to further improve the overall performance of recycled spandex fibers.

[0036] The crosslinking agent accounts for 1 to 10% of the total mass of the recycled spandex fiber;

[0037] The reinforcing agent comprises 0.5% to 3% of the total mass of the recycled spandex fiber;

[0038] The molar ratio of amine groups in the mixed amine to reactive groups on amine groups in the crosslinking agent is 1.1:1 to 3:1;

[0039] The molar ratio of the amine group of the amine chain extender to the amine group of the amine terminator is 10:1 to 30:1.

[0040] In this invention, by controlling the slightly excess of amine groups after the reaction, the spinning process is kept in a weakly alkaline environment, which inhibits the precipitation and decomposition of impurities or auxiliaries in the recovered spandex at high temperatures, such as oils on waste spandex fibers, thereby reducing the impact on the spinning system and improving spinning stability.

[0041] The method for preparing recycled spandex includes the following steps:

[0042] Polymerization step: The recycled spandex, crosslinking agent, mixed amine and reinforcing agent are mixed evenly and reacted fully to obtain the recycled spinning material;

[0043] The sources of the recycled spandex include one or more of the following: spandex waste filaments, spandex waste materials, or spandex components from waste fabrics.

[0044] Preferably, the recycled spandex is pretreated before the polymerization step;

[0045] Pretreatment includes crushing and drying at least one of the spandex components of waste spandex filaments, waste spandex materials, or waste fabrics;

[0046] In some embodiments of the present invention, the crushing process includes cutting the waste spandex filaments into spandex short fibers of 5-10 mm, and cutting the spandex components of the waste spandex material or waste fabric into particles of 5-10 mm.

[0047] The drying temperature is 90–200℃;

[0048] In some embodiments of the present invention, the polymerization step can be carried out using a screw extruder as a reactor. Specifically, the recycled spandex, crosslinking agent, mixed amine and reinforcing agent are added to the screw extruder for mixing and reaction.

[0049] The reaction temperature is 200–250°C.

[0050] Spinning steps: Using the aforementioned recycled spinning material as raw material, the material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0051] The spinning temperature is 200–250°C.

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0053] Pretreatment for recycled spandex: at least one of the spandex components in waste spandex filaments, waste spandex materials, or waste fabrics is crushed and dried.

[0054] The crushing process includes cutting spandex waste filaments into 5-10 mm spandex short fibers and cutting spandex waste or waste fabric spandex components into 5-10 mm particles.

[0055] The drying process includes drying the pulverized recycled spandex at 90–120°C for 1–5 hours to obtain pretreated recycled spandex for later use.

[0056] Example 1

[0057] 1200 kg of recycled spandex, 12.5 kg of crosslinking agent, 0.6 kg of mixed amine, and 6.5 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun yarn.

[0058] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0059] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0060] The mixed amine consists of 0.5 kg of ethylenediamine and 0.1 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.24;

[0061] The reinforcing agent is silicon dioxide.

[0062] Example 2

[0063] 1100 kg of recycled spandex, 12 kg of crosslinking agent, 1.1 kg of mixed amine, and 6 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun material.

[0064] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0065] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 4%.

[0066] The mixed amine consists of 1 kg of ethylenediamine and 0.1 kg of diethylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.88;

[0067] The reinforcing agent is silicon dioxide.

[0068] Example 3

[0069] 1000 kg of recycled spandex, 15 kg of crosslinking agent, 1.1 kg of mixed amine, and 10 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun material.

[0070] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0071] Among them, the crosslinking agent is diphenylmethane diisocyanate and polytetramethylene ether glycol react to obtain a polyurethane prepolymer with an NCO mass content of 3.5%;

[0072] The mixed amine consists of 1 kg of pentanediamine and 0.1 kg of ethanolamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 2.75;

[0073] The reinforcing agent is silicon dioxide.

[0074] Example 4

[0075] 1000 kg of recycled spandex, 20 kg of crosslinking agent, 1.6 kg of mixed amine, and 30 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spinning material.

[0076] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0077] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0078] The mixed amine consists of 1.5 kg of ethylenediamine and 0.1 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 2.19;

[0079] The reinforcing agent is hydrotalcite.

[0080] Example 5

[0081] 1200 kg of recycled spandex, 120 kg of crosslinking agent, 5.5 kg of mixed amine, and 7 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spinning material.

[0082] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0083] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0084] The mixed amine consists of 5 kg of ethylenediamine and 0.5 kg of diethylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.26;

[0085] The reinforcing agent is silicon dioxide.

[0086] Example 6

[0087] 1000 kg of recycled spandex, 20 kg of crosslinking agent, 1.6 kg of mixed amine, and 35 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun material.

[0088] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0089] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0090] The mixed amine consists of 1.5 kg of ethylenediamine and 0.1 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 2.19;

[0091] The reinforcing agent is hydrotalcite.

[0092] Example 7

[0093] 1200 kg of recycled spandex, 11 kg of crosslinking agent, 0.528 kg of mixed amine, and 6.5 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun material.

[0094] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0095] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0096] The mixed amine consists of 0.44 kg of ethylenediamine and 0.088 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.24;

[0097] The reinforcing agent is silicon dioxide.

[0098] Example 8

[0099] 1200 kg of recycled spandex, 140 kg of crosslinking agent, 6.413 kg of mixed amine, and 7 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spinning material.

[0100] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0101] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0102] The mixed amine consists of 5.83 kg of ethylenediamine and 0.583 kg of diethylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.26;

[0103] The reinforcing agent is silicon dioxide.

[0104] Example 9

[0105] 1200 kg of recycled spandex, 12.5 kg of crosslinking agent, 0.48 kg of mixed amine, and 6.5 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun yarn.

[0106] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0107] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0108] The mixed amine consists of 0.4 kg of ethylenediamine and 0.08 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 0.99;

[0109] The reinforcing agent is silicon dioxide.

[0110] Example 10

[0111] 1200 kg of recycled spandex, 12.5 kg of crosslinking agent, 0.492 kg of mixed amine, and 6.5 kg of reinforcing agent were added to a screw extruder through a mixing system and mixed to produce recycled spun yarn.

[0112] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0113] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0114] The mixed amine consists of 0.41 kg of ethylenediamine and 0.082 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.02;

[0115] The reinforcing agent is silicon dioxide.

[0116] Example 11

[0117] 1000 kg of recycled spandex, 15 kg of crosslinking agent, 1.32 kg of mixed amine, and 10 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun material.

[0118] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0119] Among them, the crosslinking agent is diphenylmethane diisocyanate and polytetramethylene ether glycol react to obtain a polyurethane prepolymer with an NCO mass content of 3.5%;

[0120] The mixed amine consists of 1.2 kg of pentanediamine and 0.12 kg of ethanolamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 3.30;

[0121] The reinforcing agent is silicon dioxide.

[0122] Comparative Example 1

[0123] 1200 kg of recycled spandex, 0.6 kg of mixed amine, and 6.5 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spinning material.

[0124] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0125] The mixed amine consists of 0.5 kg of ethylenediamine and 0.1 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.24.

[0126] The reinforcing agent is silicon dioxide.

[0127] Comparative Example 2

[0128] 1200 kg of recycled spandex, 12.5 kg of crosslinking agent, and 6.5 kg of reinforcing agent are added to a screw extruder through a mixing system and mixed to produce recycled spun yarn.

[0129] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0130] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0131] The reinforcing agent is silicon dioxide.

[0132] Comparative Example 3

[0133] 1200 kg of recycled spandex and 6.5 kg of reinforcing agent were added to a screw extruder through a mixing system and mixed to produce recycled spinning material.

[0134] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0135] The reinforcing agent is silicon dioxide.

[0136] Comparative Example 4

[0137] 1200 kg of recycled spandex, 12.5 kg of crosslinking agent, and 0.6 kg of mixed amine are added to a screw extruder through a mixing system and mixed to produce recycled spinning material.

[0138] The material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex.

[0139] The crosslinking agent is diphenylmethane diisocyanate, which reacts with polytetramethylene ether glycol to obtain a polyurethane prepolymer with an NCO content of 3%.

[0140] The mixed amine consists of 0.5 kg of ethylenediamine and 0.1 kg of cyclohexylamine, wherein the molar ratio of amine groups to crosslinking agent NCO in the mixed amine is approximately 1.24.

[0141] The spandex fiber samples (40D) obtained in the above embodiments and comparative examples were subjected to the following performance tests, and the performance results are shown in Table 1 below:

[0142] Table 1:

[0143] performance SS300(gf) DS(gf) DE(%) Spinability per day / piece Example 1 10.5 46 48 15 Example 2 10.5 50 50 15 Example 3 10.8 55 54 12 Example 4 11.5 68 70 10 Example 5 10.5 46 48 2 Example 6 11.5 68 72 15 Example 7 10.2 44 46 20 Example 8 10 42 40 5 Example 9 10 44 40 25 Example 10 10.2 45 43 20 Example 11 10.3 47 48 14 Comparative Example 1 10 40 40 45 Comparative Example 2 10.2 42 42 25 Comparative Example 3 9.8 38 40 50 Comparative Example 4 9 26 28 15 Conventional non-recycled melt-spun spandex 10.8 63 70 6

[0144] SS300: Indicates the stress when the product is stretched by 300%.

[0145] High temperature resistance: The tensile breaking strength (DS) retention rate of the product after being stretched at 2.5 times and heated to 130℃ for 40 minutes.

[0146] Alkali resistance: The retention rate of tensile breaking strength (DS) of the product after 30 minutes in a 25% alkalinity solution at 110℃.

[0147] SS300 and DS were tested using a microcomputer-controlled electronic universal testing machine in accordance with FZ / T 50006-2013 "Test Method for Tensile Properties of Spandex Filament".

[0148] Spinability: Summarize production line faults and calculate the average number of faults per 24 positions per day. 8 or less is considered excellent spinability, more than 8 but less than 20 is considered good spinability, more than 20 but less than 40 is considered average spinability, and more than 40 is considered poor spinability.

Claims

1. A type of recycled spandex fiber, characterized in that... The process involves reacting recycled spandex, crosslinking agent, mixed amine and reinforcing agent to obtain recycled spinning material, and then performing melt spinning on the recycled spinning material to obtain recycled spandex fiber. The crosslinking agent includes a polyurethane prepolymer, wherein the polyurethane prepolymer is an isocyanate-terminated polyurethane prepolymer; The isocyanate-terminated polyurethane prepolymer has an NCO content of 2-6% by mass. The mixed amine includes an amine chain extender and an amine terminator; the molar ratio of amine groups in the mixed amine to reactive groups on amine groups in the crosslinking agent is 1.1:1 to 3:1; The reinforcing agent includes one or more of silicon dioxide, hydrotalcite, silicon carbide, boron oxide, or aluminum oxide.

2. The recycled spandex fiber according to claim 1, characterized in that... The sources of the recycled spandex include one or more of the following: spandex waste yarn, spandex scrap, or spandex components from waste fabrics.

3. The recycled spandex fiber according to claim 1, characterized in that... The crosslinking agent includes a polyurethane prepolymer, which is an isocyanate-terminated polyurethane prepolymer obtained by reacting a diisocyanate and a polymeric polyol; the crosslinking agent accounts for 1 to 10% of the total mass of the recycled spandex fiber.

4. The recycled spandex fiber according to claim 3, characterized in that, The diisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, or dicyclohexylmethane diisocyanate.

5. The recycled spandex fiber according to claim 4, characterized in that, The diisocyanate mentioned is diphenylmethane diisocyanate.

6. The recycled spandex fiber according to claim 3, characterized in that, The polymeric polyols include polyether polyols, which include any one or a combination of at least two of polytetramethylene ether glycol, polyethylene glycol, or polypropylene glycol.

7. The recycled spandex fiber according to claim 1, characterized in that, The spinning process is conducted in a weakly alkaline environment; The amine chain extender comprises a diamine having 2 to 30 carbon atoms, and the amine terminator comprises a monoamine having 2 to 20 carbon atoms.

8. The recycled spandex fiber according to claim 7, characterized in that, The molar ratio of the amine group of the amine chain extender to the amine group of the amine terminator is 10:1 to 30:

1.

9. The recycled spandex fiber according to claim 1, characterized in that, The reinforcing agent accounts for 0.5% to 3% of the total mass of the recycled spandex fiber.

10. The recycled spandex fiber according to claim 7, characterized in that, The diamine having 2 to 30 carbon atoms includes one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, methylpentanediamine, methylpropylenediamine, hexanediamine, phenylenediamine, phenylenediamine, diaminocyclohexane, or hexamethylenediamine.

11. The recycled spandex fiber according to claim 7, characterized in that, The monoamine having 2 to 20 carbon atoms includes one or more of diethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine-diethylamine, dimethylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, dipropylamine, cyclohexylamine, or ethanolamine.

12. A method for preparing recycled spandex fiber as described in claim 1, characterized in that, The method includes the following steps: Polymerization step: Selected spandex waste filaments, spandex scraps, or spandex components from waste fabrics are crushed and dried to produce recycled spandex; the drying temperature is 90~200℃; Recycled spandex, crosslinking agent, mixed amine, and reinforcing agent are mixed evenly and reacted fully to obtain recycled spinning material; wherein, the crosslinking agent accounts for 1-10% of the total mass of recycled spandex fiber; the reinforcing agent accounts for 0.5-3% of the total mass of recycled spandex fiber; the molar ratio of amine groups in the mixed amine to reactive groups in the crosslinking agent is 1.1:1-3:1; the molar ratio of amine groups to crosslinking agent ensures that the spinning process is weakly alkaline; Spinning steps: Using the aforementioned recycled spinning material as raw material, the material is melt-spun through a spinneret assembly, and then spun and wound to obtain recycled spandex; the spinning temperature is 220~250℃.